This study is comparing the antiviral and clinical effects of three different combination therapies (ddI/ZDV/nevirapine vs ddI/ZDV/placebo vs ddI/placebo/nevirapine) among children with advanced HIV disease. The study closed to accrual in March 1996 and study participants are expected to have completed follow-up by the end of February 1997. During the past year nine children were followed in this study at JHU; 3 were taken off the study in order to receive open-label combination antiretroviral therapy.